Hydrogen peroxide disproportionation: time-resolved optical measurements of spectra, scattering and imaging combined with correlation analysis and simulations

Abstract

We study how time-dependent optical measurements of spectra, scattering, and imaging can be used to add to the understanding of heterogeneous reactions, compared to work performed using tools developed for homogeneous reactions. Using hydrogen peroxide disproportionation by potassium permanganate as a model reaction, we measure the entire spectrum over reaction time, enabling a clear and useful correlation analysis and assignment of chemical species in heterogeneous conditions. We measure time-dependent dynamic light scattering to study oxygen nanobubble product formation kinetics and equilibrium. We perform macroscopic video-rate reaction imaging and information-theoretic analysis to characterize reaction and transport contributions to the observed signal. To illustrate the differences arising from measuring sample subsets vs the entire system, we integrate stochastic and macroscopic numerical simulations of reaction-diffusion to study homogeneous and heterogeneous reaction conditions. We hope the tools presented here may help understanding other chemical reactions in heterogeneous conditions.